In the case of motor vehicles, the vehicle seats are almost exclusively configured so that their backrests comprise head restraints. Here, the head restraint is mostly designed as a separate construction element, which is inserted into mountings of the backrest via head restraint rods. Alternatively, the head restraint can constitute a construction unit with the backrest. Thus, the head restraint presents itself quasi as extension of the backrest towards the top. Conventional two-way passive head restraints or active head restraint systems, in particular four-way head restraints with engageable horizontal adjustment, are employed.
From WO 2006/136485 A a head restraint is known, which in the event of a rear-end impact on the motor vehicle, is designed fixed relative to the backrest and thus in a way of a conventional head restraint, or is designed so that at least a part of the head restraint can be immediately displaced in the direction of the vehicle occupant, by means of which this is designed as active head restraint. This head restraint comprises a basic body and a foam body surrounding the latter. At the front, the foam body has a contact surface for the head of a person using the vehicle seat, wherein this contact surface has a vertically running convex curvature. In the region of a front surface facing the contact surface of the foam body, the basic body also has a vertically running convex curvature. Between contact surface of the foam body and front surface of the basic body the foam body is designed relatively thick, in particular in the region of the front end of the basic body. This convex design of the front surface of the basic body, which in the region of the upper end is arranged further back than in the region of the vertical center of the front surface of the basic body, requires that upon an impacting of the head of a vehicle occupant due to an accident, the head, upon compression of the foam body in the region of the front end of the front surface of the basic body, can slide off towards the top and in the process the head is additionally subjected to a tilting moment about a horizontal axis.